1. Field of the Invention
The present invention relates to an audio and video sensing device. More particularly, the present invention relates to a compact and inexpensive integrated audio/video sensor and system capable of receiving image and sound signals synchronously and resolving image/sound sensing circuit compatibility problem.
2. Description of the Related Art
In modern society, consumer electronics products play an increasing important role in our daily life. To be popular, these electronic products must be light and compact, have a low operating voltage and consume as little power as possible. In recent years, most consumer products are aiming for portability. In other words, inventors are seeking ways to integrate formerly individual devices into a smaller unit so that the integrated product is rendered lighter and easier to carry. For example, the integration of a personal computer with a real-time video information system has permitted instant video communication through a network. Similarly, the integration of mobile phone with real-time video information system has permitted instant video communication through a wireless telephone network. Another example is the integration of audio and video sensors into a single unit.
In the past, the audio sensor and the video sensor are formed separately. FIG. 1 is a schematic cross-sectional view of a conventional video sensor. As shown in FIG. 1, a conventional video sensor 100 comprises a lens 102 on a lens mount 104, a holder 106, an infrared filter plate 108, an image-sensing chip 110, a passive component 112 and an image processor 114. The lens 102 receives light from an image, passes the light through the infrared filter plate 108 and finally focuses the light on the image-sensing chip 110. The image-sensing chip 110 transforms the received light into image signals. Thereafter, the image signals are transmitted through the peripheral circuits, for example, a passive device 112 into to the image processor 114 for further processing. In general, if the aforementioned image-sensing device is a complementary metal-oxide-semiconductor (CMOS) image-sensing module, the cost of producing the image sensor is lower and the overall size of the image sensor are smaller than a conventional charged couple device (CCD).
FIG. 2 is a schematic sectional view of a conventional audio sensor. As shown in FIG. 2, a conventional audio sensor comprises a polymer diaphragm 202, a spacer pad 204, a back plate 206, a media substance 208, an impedance converter 210 and a power source/peripheral circuit 212. In the past, carbon powder was inserted into the space between the polymer diaphragm 202 and the back plate 206. In recent years, the carbon powder has been replaced by air. When the diaphragm 202 receives any acoustic vibration, the carbon powder between two electrodes will be compressed or relaxed, therefore the impedance between the polymer diaphragm 202 and the back plate 206 is changed. The impedance is measured and converted by the impedance converter 210. The drawback of these kinds of products is their high noise content and relative instability.
Accordingly, the mechanical structure and the electronic circuits of a conventional image sensor and that of a conventional audio sensor are different. Hence, in most of the conventional audio/video sensing systems, the audio sensor and the video sensor are just assembled together for convenience. In the audio/video sensing system, the sensing device and circuits for audio sensing and image sensing are independent from each other. Therefore, a lot of space may be wasted and the cost is high. Furthermore, the images and sounds collected via the different sensing devices are not synchronous due to the compatibility of the sensing circuits. Thus, an integrated audio/video sensor is required.